[snip]
Although redesigning referral generation in slapd could streamline things, I don't quite see what issues can't be addressed using a global instance of slapo-chain. You can configure referral chasing differently for different domains using the chain-uri directive. I favor fixing only what's actually broken.
The request revolves around having different behavior for different databases. With a global slapo-chain you cannot turn off referral chasing; URIs that are not explicitly configured will still be chased.
Also in terms of logical abstraction the current behavior is wrong; the frontend should of course generate the default_referral responses but updateref is a per-backend item and should be generated at the backend layer. Ideally this would all have been fixed to behave correctly by moving all replication support into an overlay, where it properly belongs. As an interim step it would be trivial to write an updateref overlay that supersedes the current updateref behavior.
As I said, I recognize the usefulness of such a change: I first moved replication into an overlay (ITS#4261). I'm questioning its need for the case at hand. Perhaps allowing slapo-chain to ignore some URIs would be easier to implement, and generally useful in other applications.
In any case, I might spare some time to revitalize (ITS#4261), now that slurpd is no longer around and thus things simplify significantly.
p.